CROSS LAYER ADAPTATION FOR QoS IN WSN

Abstract

In this paper, we suggest Quality of Service familiar MAC protocol for Wireless Sensor Networks its cross layer extension to network layer for providing QoS in  delay sensitive WSN scenarios. In Wireless sensor networks, there can be 2 types of traffics; first one is event driven traffic which needs instantaneous observation and the second one is periodic reporting. Event driven  traffic is classified as Class I (delay sensitive) traffic and periodic reporting is classified as Class II (Best Effort) Traffic. MAC layer adaptation can take place in terms of (i) Dynamic contention window adjustment per class, (ii) Minimizing the delay experienced by changes in Sleep schedules (DSS) of communicating nodes by randomly altering Duty Cycle based usages and DSS delay of class I traffic, (iii) Different DIFS (DCF Inter Frame Spacing) per class, (iv) modifying all the three patterns suggested above at the same time. Cross layer extension is also proposed, in which MAC layer uses network layer next hop information for better adaptation of duty has based on DSS delay. Routing protocols can utilize MAC layer parameter DSS delay to select the routes which offer least DSS delay latency, thereby minimizing the overall end-to-end delay.